This study tested two long-standing assumptions in education: that reading ability in the elementary grades is differentiated by sex and that boys experience a higher incidence of reading disability than do girls. In addition, three biological explanations for this difference were tested: maturational lag, cerebral dominance, and vulnerability of the male organism. A Hebrew reading-comprehension test was administered to second graders and fifth graders in an Israeli kibbutz, chosen because of the lack of separation of boys and girls, the relative lack of differentiation of socialization practices, and the availability of uniformly maintained medical, developmental, and educational records. Results showed no differences in gender in reading level and reading readiness, in frequency of occurrence of reading disability, in maturational lag, in mixed dominance, nor in 12 selected indices of psychopathology in children. Tables of findings illustrate the text. (JM)